Hi,
while using the device, I noticed that, in many situations, the device needs a significant amount of time to perform "requested" actions.
The problem is that, usually, the user is not "informed" in any way that the device is doing something (I "click" something and then I do not know if my "request" was accepted and the device is "processing" it or not).

So, I'd like to propose the following.

Each time the device "reads" (or "writes") something from (to) any file, either from the "Internal Storage" or from the "SD Card" or from any "system directories" (e.g. when it loads and starts an additional utility and/or library), the "blue LED", which resides right below the "joystick", should light up / blink.
This would serve as a general purpose "disk used" indicator (and then the user immediately sees that there's something happening).

I think the LED is a good idea, and that is what is done on the PocketBook Pro devices. I wanted to point out that some people complained about this feature because it ate up some battery power (probably shortening the time between charges from 30 to 29.5 days). I guess the spinning wheel would produce the same complaint. I find it amusing that it is hard to make an improvement without someone seeing it as a step backwards, no matter how good the idea.